A simplified oscillator array with a plurality of series-connected (arrayed) oscillators has been suggested (e.g. refer to patent documents 1 to 3). In this case, it is expected to be a power transmission unit of a high efficiency without a distribution loss, and it is also possible to reduce a scale of the apparatus in the microwave power transmission.    Patent document 1: Japanese Patent Application Laid Open NO. 2002-299943 (Claim 1)    Patent document 2: Japanese Patent Application Laid Open NO. 2003-133952 (Claim 1)    Patent document 3: Japanese Patent Application Laid Open NO. 2003-258556 (Claim 1)